Tobacco filters

ABSTRACT

Tobacco smoke filters mainly consisting of ethylene-vinyl acetate copolymer containing 10 to 80 mol percent of ethylene and saponified to an extent of more than 85 percent.

United States Patent [191 Sato et a1,

[ TOBACCO FILTERS [75] Inventors: Wasulre Sato; Seijiro Yamamoto,

both of Tokyo; Nobnaki Kuwabara; Shigeru Adachi, both of Yokohama,

all of Japan [73] Assignee: Shown Denko K.1K., Tokyo, Japan [22] Filed: Mar. 21, 1973 [21] App]. No.: 343,421

[30] Foreign Application Priority Data UNITED STATES PATENTS 3,173,427 3/1965 Tamblyn et al 131/269 X Dec. 24, 1974 3,290,207 12/1966 Magat et a1. 131/269 UX 3,528,433 9/1970 Johnson et al 131/269 X 3,608,564 9/1971 Hiroshima et a1. 131/269 FOREIGN PATENTS OR APPLICATIONS 56,304 6/1971 Japan 131/269 Primary ExaminerMelvin D. Rein Attorney, Agent, or Firm-Kemon, Palmer & Estabrook [5 7 ABSTRACT Tobacco smoke filters mainly consisting of ethylenevinyl acetate copolymer containing 10 to 80 mol percent of ethylene and saponified to an extent of more than 85 percent.

12 Claims, No Drawings This invention relates to tobacco smoke filters capable of effectively eliminating harmful substances such as nicotine and tars from tobacco without absorbing its original flavor.

As is well known, tobacco smokes contain alkaloids such as nicotine, organic acids, phenolic components, water, carbon dioxide and a large amount of black tarry matter. Among these ingredients, particularly the polar substances such as basic and acid ones have a high boiling point and a great affinity for water, so that they are very likely to be retained in the body of a smoker and apply a harmful load on the lungs, liver, kidney and stomach.

Various attempts have hitherto been made to eliminate the above-mentioned harmful ingredients, but without any success.

The devices proposed to date include, for example, a bundle of cellulose acetate fibers treated with a plasticizer and fibers of rayon or polypropylene bonded'together with an adhesive into a required shape. However, all these attempts are intended to remove the aforesaid harmful components simply by physical process'es such as cooling, condensation and adsorption, failing to display a fully desired effect. Study has also been made on the methods of manufacturing tobacco filters containing certain kinds of organic or inorganic material, for example, organic acids such as oxalic acid, malic acid and tartaric acid or fine powders of carbonates and phosphates of magnesium and calcium. How ever, all such processes reduce the flavor of tobacco to gratify a smokers taste, present difficulties in production of such filters, are accompanied with economic disadvantages andfail fully to eliminate the aforementioned harmful ingredients of tobacco.

It is accordingly an object of this invention to provide tobacco smoke filters capable of very effectively removing harmful materials such as nicotine and tars from tobacco.

Another object of the invention is to provide tobacco smoke filters attaining the prominent elimination of said harmful ingredients and permitting a user to inhale tobacco smokes with little effort.

Still another object of the invention is to provide an industrially advantageous method of manufacturing tobacco smoke filters of good breatheability having a high capacity to eliminate harmful substances from tobacco.

According to an aspect of this invention, there are provided tobacco smoke filters mainly-consisting of ethylene-vinyl acetate copolymer containing to 80 mol percent of ethylene and saponified to an extent of at least 85 percent.

According to another aspect of the invention, there are provided tobacco smoke filters consisting of more than percent by weight of ethylene-vinyl acetate copolymer containing 10 to mol percent and saponified to an extent of more than 90 percent and less than 80 percent by weight of polyolefins.

According to still another aspect of the invention, there is provided a method of manufacturing tobacco smoke filters having 50 to percent porosity which comprises first preparing the raw material of tobacco smoke filters which consists of 100 to 50 parts by weight of powders, fibers or mixtures thereof of ethylene-vinyl acetate copolymer containing 20 to 65 mol percent ofethylene and saponified to an extent of more A than percent and 0 to 50 parts by weight of powders,

fibers or mixtures thereof of polyolefins; and thereafter treating said tobacco smoke filter material by either of the following processes (1) and (2):

l. to let water be absorbed in the tobacco filter material at the rate of 5 to parts by weight based on 100 parts by weight of said filter material and heat the soaked mass to a temperature of 55 to C,

percent-of ethylene and saponified to an extent of 85 percent or preferably more than 90 percent. A similar copolymer having a composition falling outside of the above-mentioned range presents a considerably low capacity to eliminate nicotine and tarts from tobacco smoke.

The saponified ethylene-vinyl acetate copolymer of i this invention can be prepared by first dissolving said copolymer in lower alcohol or aromatic hydrocarbon solvent or a mixture thereof and adding acid or alkali to the resultant solution for saponification. It has also been experimentally confirmed that tobacco smoke filters according to this invention will have a more increased capacity to eliminate the harmful components of tobacco smoke by incorporating any of the following additives:

glycols such as ethylene glycol, propylene glycol, butane diol, pentadiol, diethylene glycol, triethylene gly col, tetraethylene glycol and dipropylene glycol, water and trivalent alcohol such as glycerine.

While the above additive and the saponified ethylenevinyl acetate copolymer should preferably be fused together, it is also possible first to form said saponified copolymer into, for example, fibers and then pass said fibers through an atmosphere of said additive so as to cause said additive to permeate the fibers or be adsorbed thereto. It is further desired that said additive be used in an amount of 0.05 to 10 parts by weight based on 100 parts by weight of the saponified copolymer.

Tobacco smoke filters of this invention mainly consisting of ethylene-vinyl acetate copolymer containing 10 to 80 mol percent and saponified to an extent of more than 85 percent indeed offer the advantage of very effectively adsorbing the harmful ingredients of tobacco such as nicotine and tars. But said advantage is offset by the fact that where several cigarettes are smoked through said filter inserted into, for example,

a pipe, the unduly high capacity of the filter to adsorb the harmful ingredients causes large amounts of said ingredients to beaccumulated in the filter, with the result that the filter is plugged with the adsorbed material in a relatively short time, obliging a smoker to use greater effort in inhaling tobacco smokes from a fresh cigarette filter.

Therefore, the above-mentioned filter can indeed be very suitably used as an attachment to a single cigarette which evolves a small amount of tobacco smokes. But where said filter is inserted into a tobacco smoke holder, it presents the drawback that it has to be replaced by a fresh one in a short time due to adsorbed material plugging said filter relatively early.

In contrast, a tobacco smoke filter consisting of 80 to 20 parts by weight of ethylene-vinyl acetate copolymer containing to 80 mol percent of ethylene and saponified to an extent of 85 percent or preferably more than 90 percent and to 80 parts by weight of polyolefins has been formed to save a smoker from much effort in inhaling tobacco smokes from a large number of cigarettes over a considerable period. Namely, though the filter consisting of the above-mentioned mixture eliminates smaller amounts of the harmful ingredients of tobacco per unit volume than a filter only consisting of the saponified copolymer, yet the former filter does not substantially obstruct a smokers inhalation of tobacco smokes over a relatively long period. Therefore, a tobacco filter formed of a mixture of said saponified copolymer and polyolefins is adapted to be used as an insert in a tobacco holder, for example, a pipe.

Where the above-mentioned composite tobacco smoke filter contains more than 80 percent by weight of the polyolefin, namely, less than 20 percent by weight of the saponified ethylene-vinyl acetate copolymer, then said filter is undesirably decreased in the capacity to eliminate the harmful components of tobacco. Conversely, where the composite tobacco filter includes less than 20 percent by weight of the polyolefin, then said polyolefin can not display its full effect, rendering the filter unadapted to be used in smoking muchtobacco over a long period, because it obstructs a smokers inhalation of tobacco smokes due to adsorbed material plugging the filter in a relatively short time. As used herein, the term polyolefins is defined to include polypropylene, high density polyethylene, low density polyethylene and copolymers mainly consisting of these polyolefins and other minor components. These polyolefins have a combination of favorable properties of preventing the subject tobacco smoke filter from presenting increased resistance to a smokers inhalation of tobacco, presenting littlehygroscopicity, evolving no toxic gases and being readily fabricated into fibers.

Where a saponified ethylene-vinyl acetate copolymer or a mixture of said copolymer and the aforesaid polyolefins is to be used as a tobacco smoke filter, it is advised to form these filter materials into fibers, split fibers, films and moldings (for example, pipe cartridges), as need requires. Particularly preferred are the fibers or split fibers which have a large area of adsorption. Fabrication of the aforesaid saponified ethylene-vinyl acetate copolymer or a mixture of said copolymer and the polyolefins into fibers may advisably be carried out, for example, by the customary melt spinning or split fiber process. The fibers thus prepared are preferred to have a thickness of several or 10 and odd denier units. Manufacture of a tobacco filter from said fibers may be effected by first bundling the fibers in a certain direction to form a tow and then forming a thin crust on said tow by application of, for example, heat, or surrounding the tow with a thin piece of synthetic resin or paper. Further, it is possible to fill a separate vessel with said tow or individual fibers in bulk.

A tobacco smoke filter according to this invention may also be produced by the following process. Namely, the raw material of said tobacco filter is first prepared from 100 to 50 parts by weight of powders, fibers or mixtures thereof of ethylene-vinyl acetate c0- polymer containing 20 to 65 mol percent of ethylene and saponified to an extent of more than percent and 0 to 50 parts by weight of powders, fibers or mix tures thereof of polyolefins. Thereafter, the raw material thus prepared is further treated by either of the following processes (I) and (2):

l. to let water be absorbed in said raw material at the rate of 5 to parts by weight based on 100 parts by weight of said raw material and heat the soaked mass to a temperature of 55 to 150C,

2. to apply saturated steam at 80 to C to said raw material.

The above-mentioned additional treatment enables the filter material to be fabricated at a relatively low temperature, preventing the final filter product from being discolored by the high heat to which the product might otherwise be subjected at the time of fabrication. The reason is assumed to be that the water absorbed in the filter material or the saturated steam ejected thereon acts as a sort of plasticizer to decrease the softening and melting points of said filter material. Further, the aforesaid treatment causes the powders or fibers constituting the filter material to contact each other tangentially with the resultant growth of numerous fine cavities. When the water filled in these cavities is dried off, there is obtained a tobacco filter of very great breatheability having a porosity of 50 to 85 percent.

The conditions under which the subject tobacco filter product is fabricated, that is, the amount of water absorbed in the filter material or the temperature of saturated steam ejected thereon and the temperature and length of time required for said fabrication can be freely chosen according to the ethylene content, the extent of saponification and the final form of the ethylene-vinyl acetate copolymer constituting the filter material. Namely, where such copolymer low in ethylene or highly saponified is fabricated with the temperature unchanged, then it is necessary to add a large amount of water. Conversely, where such copolymer rich in ethylene or slightly saponified is fabricated, then water has only to be added in a small amount.

The above description also holds truth with application of saturated steam. Namely, fabrication of the aforesaid copolymer low in ethylene or highly saponified requires saturated steam to be applied at a higher temperature and a longer time than in the reverse case.

This invention will be more fully understood by refer ence to the examples and controls which follow.

EXAMPLES 1 TO 4 AND CONTROLS 1 TO 4 Samples of ethylene-vinyl acetate copolymer containing 20, 35, 40 and 55 mol percent of ethylene re-' spectively and saponified to an extent of more than 98.5 percent alike were formed into fibers on a melt spinning extruder. The fibers were bundled into a tow having 55,000 deniers in total and containing 20 clumps per inch with monofilaments measured to have about 4 deniers. Samples of said tow were fabricated into four types of tobacco filter each 102 mm long and 24.7 mm in peripheral length on a tobacco filter manufacturing machine. Each type of filter was attached to an end of acigarette in a length of 17 mm. Comparative tests were carried out on these four types of tobacco filter and those of the controls 1 to 4, the results being presented in Table 1 below. Control 1 denotes the conventional cellulose acetate tobacco filter; Control 2 represents ethylene-vinyl acetate copolymer containing 8 mol percent of ethylene and saponified to an extent of more than 98.5 percent; Control 3 indicates ethylene-vinyl acetate copolymer containing 85 mol per cent of ethylene and saponified to an extent of more than 98.5 percent; and Control 4 shows ethylene-vinyl acetate copolymer containing 40 mol percent of ethylene and saponified to an extent of 80 percent. Where EXAMPLES 5 TO 7 AND CONTROL 5 Samples of ethylene-vinyl acetate copolymer containing 15, 30 and 50 mol percent of ethylene respectively and saponified to an extent of more than 99.0 percent alike were formed into films each 50 microns thick on a T-die extruder. After stretched to 2.5 times the original size, the films were made into fibrils on a splitter. These fibrils were fabricated into tobacco fil' ters. The same tests as in the preceding case were made on said filters, the results being presented in Table 2 below. Control 5 represents the conventional cellulose acetate tobacco filter.

saponification was carried out to an extent of less than Table 2 85 percent as in the case of Control 4, the saponified mass stuck to an extruder screw, preventing the suc- Ethylene weght i content (mg/17mm) to inhalation of ceeding portion of the raw material from travelling for- (101% tobacco smoke ward through the extruder with the resultant failure to (mm fabricate a tobacco filter. Accordingly, monofil aments 20 Example 5 15 H5 59 were first obtained by solution spinning (using dlmethyl 6 113 60 formamidean aqueous solution of sodium sulfate) and 7 H0 58 tobacco smoke filters were prepared from said monofilcontrol 5 11b 53 aments. 25 Table l Ethylene Filt r r i tan Elimination Elimination of Elimination of content Filter weight to inhalation of of tars 7 "lemme (17) Phenolic mp (mol (mg/17mm) tobacco smoke 3O ((7') Example I 20 110 57 2 112 54 7 82 74 3 H7 4 55 l 17 54 Control 5 42 3 8 35 Control l H0 53 2 8 H3 58 3 H5 53 EXAMPLES 8 TO ll AND CONTROLS 6 AND 7 4 40 H5 63 Samples were prepared by mixing 100 parts by 40 weight of ethylene-vinyl acetate copolymer containing 40 molpercent of ethylene and saponified to an extent of 99.5 percent with 7 parts by weight of any of the var- Elimination Elimination f Elimination f ious additives given in Table 3 below. Each mixture was oftarsU/r) nicotine(%) phenolic compomade into an inflation film. 60 microns thick. After nemsw) 45 stretched to 3.0 times the original size, the film was Example 1 75 65 93 formed into fibers on a splitter. Various types of to- 2 82 72 92 bacco filters prepared from said fibers were sub ected 3 28 to substantially the same tests in the preceding cases, 4 the results being set forth in Table 3 below. Control 6 Comml 1 35 g ()0 50 denotes additive-free ethylene-vinyl acetate copolymer 2 52 2 93 which contained 40 mol percent of ethylene and sapon- 3 42 39 52 ified to an extent of 99.5 percent, and Control 7 repre- 4 5t 40 7s a tents the conventional cellulose acetate tobacco filter.

Table 3 Filter Filter resist- Elimina- Elimina- Addmves we: ht ance to inhalation of tion of (mg/l mm) tion of tobacco tars 72) nicotine.

smoke (mm H O) V! Example 8 Ethylene 11s 58 93 glycol 9 .4 butane [I8 60 88 diol ll) Dicth lcnc 1 lo 63 94 8'6 lgco l 1 i...@ l 15 (15 92 X4 hexane triol Filter Filter resist- Elimina- Elimina- Additives weight ance to inhalation of tion of (mg/17mm) tion of tobacco tars nicotine smoke (mm H O) Control 6 117 60 83 73 7 1 10 58 38 EXAMPLES 12 TO 17 AND CONTROLS 8 TO 12 Samples of cartridge type tobacco smoke filters were fabricated on an injection molding machine from a mixture of 100 parts by weight of ethylene-vinyl acetate copolymer containing 35 mol percent of ethylene and saponified to an extent of 98.5 percent and various proportions of glycerin shown in Table 4 below. After EXAMPLE 18 AND CONTROL l3 Fibers prepared from a mixture of 50 parts by weight of ethylene-vinyl acetate copolymer containing 42.0 mol percent of ethylene and saponified to an extent of 98.5 percent and 50 parts by weight of polypropylene (manufactured by Showa Yuka K.K. under the trademark Shoallomer MA 410) were bundled into a tow inserted into a g 'f holder Said Cartridge type having 55,000 deniers in total and 20 clumps per inch filters Y sublecteghto g ll smoklggdtests with monofilaments measure to have about 4 deniers. as m the precefhflg cases 6 a mesa Sapom Said tow was made into a tobacco filter 102 mm long .contammg more than 12 parts y and 24.7 mm in peripheral length. The filter thus preglyfcerme f to extruger Screw l g It was pared was attached to one end of a cigarette in a length i a Sal 5. mtoim zjT s g g fgfig 20 of 17 mm. Comparative tests were made on said tomgt e Succee mg pm 0 g bacco filters and Control 13 representing the convenforward through the extruder with the resultant failure tional cellulose acetate tobacco smoke filter w|th reto produce a tobacco filter from such material.

spect to resistance to inhalation of tobacco smoke, y y of Compamom the same smokmg tests were 25 elimination of the harmful ingredients of tobacco and d Controls 8 to Control 8 represents the the flavor of tobacco enjoyed by a smoker through all conventional cellulose acetate tobacco smoke filter, these filters the results being presented in Table 5 and Controls 9 to 12 all denote cartridge type tobacco 10w.

' Table 5 Filter re sistance to Elimina- Elimina- Elimination inhalation tion of tion of of phenolic of tobacco tars nicotine components Flavor smoke ('7 (mm H O) Example 18 54 67 61 92 Soft Control 13 Slightly (Conven- 53 38 60 acrid tional filter) smoke filters. Control 9 shows the one prepared by re- EXAMPLES 19 TO 22 AND CONTROL 14 ceiving glass particles in a polystyrene case. Control 10 1 indicates the one prepared by filling a polystyrene case There was P p allow a g 50,000 deniers m with silica gel particles. Control 11 indicates a hollow total and 18 clumps PeT1nCh Wll1h monofilamfimsfnfiapolystyrene case b i a i l h i which t sured to have about 4.5 deniers from fibers consisting bacco smokes introduced are condensed by the action of either or a mixture of ethylene-vinyl acetate copolyof their adiabatic expansion and collected on the inner mer containing 35.5 mol percent of ethylene and sasurface of said case. Control 12 is a cartridge type toponified to an extent of 99.2 percent and polypropylbacco filter prepared by filling a polypropylene case ene (manufactured by Showa Yuka K.K. under the with particles of foaming rubber. trademark Shoallomer FA 310) used in the propor- The same smoking tests were made on both Examtions shown in Table 6 below. Said tow was formed into ples 12 to 17 and Controls 8 to 12, the results being a continuation of rod-like filter 20.1 mm in peripheral given in Table 4 below. length. Said elongate rod-like filter material was cut up Table 4 Amount of Filter resist- Elimina- Eliminaglycenne Filter ance to inhalation of tion of added weight tion of tobacco tars nicotine (parts by (mg) smoke (mm H O) ("/1) weight) Example 12 0 630 62 75 65 13 0.05 631 65 78 69 14 0. l 630 (i2 80 70 15 l .632 (13 82 72 lo 5 (v. 1 (11 R8 75 I7 lo mo 0: 9o

Control 8 I10 58 42 38 9 1390 52 40 32 It) I720 60 43 35 l l 525 53 53 45 12 770 56 32 35 into divisions 33 mm long. Said divided portions were each inserted into a cartridge, which in turn was fitted into a pipe. Tests were carried out by smoking twenty Japanese cigarettes bearing the trademark Hi-lite, through said loaded pipe, the results being presented in weight of ethylenevinyl acetate copolymer containing 78 mol percent of ethylene andsaponified to anextent of 96.5 percent and 25' parts by weight of high density polyethylene (manufactured by Showa Yuka K.K. under the trademark Sholex 6009M); Said tow was.

Table 6 below. As apparent from Table 6, a filter (Ex fabricated into a rod-like filter, which was inserted into ample 19) consisting of said saponified ethylene-vinyl a Cartridge mm In Inner diameter andi35 gacetate copolymer alone prominently eliminated the A kmg as earned outlwlthlaplpe loadedlwltht harmful ingredients of tobacco, but was ready to be said cartridge, the results being presented iniTiable 7' plugged with absorbed material. A filter (Control 14) below. prepared from polypropylene alone eliminated small amounts of the harmfulingredients of tobacco and consequently rendered the smoked cigarette fiavorless, Tame 7 though said filter was little plugged with adsorbed material. In contrast, filters (Examples 20 to 22) formed 15 of a mixture of said saponified ethylene-vinyl acetate Resistance to inhalation copolymer and polypropylene saved a smoker from (mm much effort throughout the smoking of the abovemen- Before Af ki g Af smoking tioned twenty cigarettes and eliminated proper smoking ten cigarettes twenty cigarettes amounts of the harmful components of tobacco, en- 20 Example 23 72 105 N7 ablmg said cigarettes to give forth good flavor.

Elimination of nicotine and tars (mg/cigarette) After After After Flavor of cigarettes smoking smoking smoking evaluated by smoking one ten twenty testers cigarette cigarettes cigarettes (a erage) (average) Example 23 12.6 12.1 11.7 Judged soft and flavorful by 7 5% of the testers Table 6 Ratio of blending Resistance to inhalation (parts by weight (mm H O) Samples Saponl- After smoking After smoking fied co- Pol Before ten twenty polymer propy ene smoking cigarettes cigarettes Example 19 100 O 83 130 180 20 8O 20 83 99 115 21 50 97 109 22 2O 80 80 84 84 Control 14 0 100 76 76 77 Elimination of nicotine and tars (mg/cigarette) Samples Twenty Flavor of cigarettes One ctga'- Ten cigacigaevaluated by smoking [CH8 rettes rettes tESIfi'S (average) (average) Example 19 16.4 14.3 13.5 Jud ed flavorful by 65 not the testers Jud ed soft and flavor- 20 15.4 14.0 12.6 ful y859'rofthe testers I Judged very son and 21 l 1.3 10.7 10.2 flavorful by of the testers Judged flavorful by 75% y of t e testers. but 22 10.1 9.8 9.4 slightly flavorless by i the remainder, though the filter facilitated smoking Jud ed flavorful by 20% Control 14 6.9 6.7 6.5 oft e testers but flavorless by the remainder EXAMPLE 23 EXAMPLE 24 A tow having 48,000 deniers in total with monofilaments measured to have about 3.5 deniers was prepared from meltspunfibers' consisting of 75 parts by parts by weight of powders of ethylene-vinyl acetate copolymer containing 35.5 mol percent of ethylene and saponified to an extent of 98.5 percent(said powders had a particle size of 35 mesh pass and a bulk ing water on the outside thereof. After vacuum dried overnight at 20C, the filter thus molded had a porosity of 79 percent and an inhalation resistance of 72 mm H O. When a cigarette was smoked through a pipe loaded with the filter, the filter was found to have good breatheability and also render the cigarettes smoked therethrough veryflavorful. As measured by the customary process, said filter eliminated 80 percent of tars, 72 percent of nicotine and 93 percent of phenolic components contained in tobacco.

Control 15 It was tried to prepare a' tobacoo smoke filter from the same copolymer as used in Example 24 excepting that water was impregnated in said copolymer in amounts of 50 and 100 parts by weight each time and the mass was heated 5 minutes at 50C. In this case, the powders of said copolymer were insufficiently fused together, failing to be used as a filter material. Further where said powders were treated by incorporating 3 parts by weight ofwater and heating for 7 minutes at 160C and 3 minutes at 200C each time, said powders were insufficiently fused together in the former treatment and discolored yellow and too closely fused -to-' gether in the latter treatment. The powders of Said copolymer treated by either of the above processes were found unadapted to be used as a filter material.

EXAMPLE 25 Fibers of 8 to 10 deniers were prepared by melt spinning at 240C from a mixture of 100 parts by weight percent acetate copolymer containing 29.8 mol percent of ethylene and saponified to an extent of 95.4 percent (an aqueous solution of phenol containing percent of water in which said copolymer was dissolved was measured to have an intrinsic viscosity of 1.05 dl/g the above-mentioned melt spun fibers on a refiner roll unit were impregnated with 10 parts by weight of water. The mass was filled in the same type of mold as used in Example 24 and heated 3 minutes at 140C, followed by the same drying operation. The filter thus molded had a porosity of 75 percent and an inhalation resistance of 73 mm H O, presenting good breatheabil ity and rendering the cigarettes smoked therethrough very flavorful. Further, said filter eliminated 82 percent of tars, 71 percent of nicotine and 92 percent of phenolic components contained in tobacco.

Control 16 It was tried to mold a tobacco smoke filter from the same copolymer as used in Example 25 excepting that.

the copolymer was impregnated with 10 parts by weight of water and heated 1 minute at 170C and parts by weight of water and heated 5 minutes at 50C I each time. The former treatment only resulted in a narrow molded mass which presented an undulating surface and was fused very hard up to the interior, while the latter treatment prevented the mutual fusion of ,at 30C) and 3 parts by weightof glycerine. 100 parts,

by weight of pulpy fibers obtained by further splittingpulpy fibers. Thus either treatment was found unsuitable to provide a desired tobacco smoke filter.

EXAMPLE 26 Fibers of 4 deniers were prepared by melt spinning and subsequent stretching from ethylene-vinyl acetate copolymer containing 35.5 mol percent and saponified to an extent of 99.8 percent (an aqueous solution of phenol containing 20 percent of water in which said copolymer was dissolved was measured to have an intrinsic viscosity of 0.95 dl/g at 30C). 25,000 of such fibers were assembled into a tow bearing 20 clumps per inch obtained by a clumping process. Said tow was immersed in warm water at 30C to be impregnated with 50 parts by weight of water (including adsorbed water) based on 100 parts by weight of said tow. Said waterimpregnated tow was conducted into a pipe 0.8 cm, in diameter, heated 1 minute at a temperature of 80C from the outside of the pipe. After fully dried, the tow was taken out of the pipe and cut up 1.7 cm long in' small pieces. Tobacco smoke filters consisting of the cut pieces of said tow had a porosity of 80 percent and an inhalation resistance of 68 mm H O. The peripheral wall of the filter was coated with a thin crust as the result of the above heat treatment and the interior thereof consisted of an ideal fibrous structure.

As measured by the customary process, the filter eliminated 82 percent of tars, 73 percent of nicotine and 91 percent of phenolic components contained in tobacco.

EXAMPLE 27 The same kind of clumped tow as used in Example 26 was conducted into a porous pipe 0.8 cm in diameter and having theperipheral wall bored with 50 holes per square centimeter. The tow was treated 5 seconds with saturated steam at l 10C. After cooled and dried, said tow provided a filter having a porosity of 81 percent and an inhalation resistance of 60 mm H O with the peripheral surface alone coated with a thin crust due to the fibers being fused together and the interior formed of an ideal fibrous structure.

As measured by the customary process, the filter thus prepared eliminated 83 percent of tars, 72 percent of nicotine and 92 percent of phenolic components contained in tobacco.

EXAMPLE 28 A mixture of 30 parts by weight of powders of ethylenevinyl acetate copolymer containing 35.5 percent of ethylene and saponified to an extent of 94.5

PERCENT (said powders had a particle size of 28 to 35 mesh and a bulk density of 0.25 and an aqueous solution of phenol containing 20 percent of water in which said powders were dissolved was measured to have an intrinsic viscosity of 1.10 dl/g at 30C) and parts by weight of pulpy fibers obtained by finely splitting on a refiner roll unit fibers of about 10 deniers prepared by melt spinning from powders of ethylene-vinyl acetate copolymer containing 35.5 mol percent of ethylene and saponified to an extent of 99.8 percent (an aqueous solution of phenol containing 20 percent of water in which said powders were dissolved was measured to have an intrinsic viscosity of 0.92 dl/g at 30C) was filled into a metal mold 0.8 cm in diameter and 1.7 cm

long with the peripheral wall bored with 20 holes per square centimeter. The mass was treated seconds 'with saturated steam at 120C. After cooled, the mass was taken out of the mold and dried, providing a filter What we claim is;

1. Tobacco smoke filters adapted for use with a to bacco smoke article and of a shape to be inserted in the I smoke passage of such tobacco smoke article which having a porosity of 71 and an inhalation resistance 5 -i a mixture f 80 to 20 pa'rts b i h f- 0 75 m H2O- The fi t had its p iph ral su a polymer material and 20 to 80 parts by weight of polyalone coated with a thin crust due to the fibers being olefin material, said copolymer material consisting of fused together as the result of treatment with saturated ethylene-vinyl acetate copolymer containing to 80 steam and its interior formed of fibers tangentially cono o hylene, which p ym r has been p n tacting each other. Further, the filter eliminated 82 l0 fled to an ent of at least 85 percent and said polyoleof tars, 70 percent of nicotine and 92 percent of phefin material is selecuqd from the g p Consisting of nolic components contained in tobacco polypropylene and polyethylene, said copolymer material and said polyolefin material being in the form of fi- EXAMPLES 29 TO 33 AND CONTROLS 17 AND 18 b li fib fil or moldi gs,

' I 2. Tobacco smoke filters as claimed in claim 1 The Same type of metal mold as used in Example 28 wherein said copolymer material and said polyolefin material are in the form of fibers. was fined wlth powders of ethylene'vmyl acetate -3 Tobacco smoke filters as claimed in claim 1 for use polymer containing 38.0 mol percent of ethylene and tobacco Smoking pipes saponified to an extent of percent (the powders 4. A tobacco smoke filter as claimed in claim 1 for had a particle size of 28 to 35 mesh, and a bulk density attachment to a single cigaretm and an aqueous Solution of Phenol containing 5. Tobacco smoke filters as claimed in claim 1 for use 20 percent of water in which the powders were dis-. i h a Cigarette h l soved had an intrinsic viscosity of 0.90 dl/g at 30C) 6. Tobacco smoke filters as claimed in claim 1 which i and powders of low density polyethylene having a partiare t id filt W cle size of mesh pass and a bulk density of 0. 15, said 7 A tobacco smoke filter adapted for use with a two yp of Powders being mixed in the ratios give" in bacco smoke article and of a shape to be inserted in the Table 3 below to P p Samples- Each Sample was smoke passage of such tobacco smoke article, said filtreated 10 SfiCOlldS with saturated steam at 100C, proter having a porosity f to percent and corfiprig- Viding a filter Whose P y and inhalation resistance, 30 ing as essential filter material ethylene-vinyl acetate coas well as the capacity to eliminate nicotine, tars and polymer t i i 10 t 80 l p nt eth le d phenolic components are shown in Table 8 belo having the vinyl acetate moiety thereof saponified to an which also presents the properties of filters represented extent of at least 85 percent, said filter material being by Controls 17 and 18. Control- 17 denotes a filter conin the form of fibers, split fibers films or moldings. sisting of the same kind of saponified copolyme as in 8. A tobacco smoke filter of claim 7 wherein said 00- EXamPICS 29 33 mixed with low density Polyethylene polymer contains 20 to 65 mol percent ethylene and is in the ratio of to 60 and Control 18 shows the conin the f f fib vemmnal cellulose acetate filter AS apparent from 9 A tobacco smoke filter of claim 8 wherein said sa- Table 8, tobacco filters (Examples 29 to 33) according 4 ponification extent is a least 90 percent. to this invention are all an ideal type having good breatheability and excellent capacity to adsorb or ab- 9 A clgareue W attached ,fiher Compnsmg as Serb the harmfulvingrediems of tobacco. sential-filter material ethylene-vinyl acetate copolymer containing 10 to 80 mol percent ethylene and having Table 8 5 the vinyl acetate moiety thereof saponified to an extent I I of at least 85 percent, said filter material being in the MXmg form of fibers, split fibers, films or moldings. Saponified copolymer Low density poly- 11. The method of filtering tobacco smoke in a to- (pam) ethylene (pans) 5O bacco smoke article which comprises passing the to- Example 29 100 0 bacco smoke through a filter which comprises as essen- 2 tial filter material ethylene-viny1 acetate copolymer 60 0 containing 10 to 80 mol percent ethylene and having 33 5O the vinyl acetate moiety thereof saponified to an extent Control 17 40 55 of at least 85 percent, said filter material being in the 18 form of fibers, split fibers, films or moldings.

Properties of filters Resistance Porosity to inhala- Elimina- Elimina- Elimination of (7( tion tion of tion of phenolic com- (mm H O) tars nit(:p7ti)ne ponents 7:)

Example 29 77 72 82 7O 91 30 78 69 80, 68 90 31 77 68 71 65 85 32 76 65 6O 82 33 79 72 60 52 69 Control 17 79 e3 50 45 52 18 53 35 38 60 12. The method of claim 11 wherein said filter consaid copolymer with to 80 parts by weight of polytains a mixture of 80 to 20 parts by weight of fibers of ethylene fibers. 

1. TOBACCO SMOKE FILTERS ADAPTED FOR USE WITH A TOBACCO SMOKE ARTICLE AND OF A SHAPE TO BE INSERTED IN THE SMOKE PASSAGE OF SUCH TOBACCO SMOKE ARTICLE WHICH COMPRISES A MIXTURE OF 80 TO 20 PARTS BY WEIGHT OF COPOLYMER MATERIAL AND 20 TO 80 PARTS BY WEIGHT OF POLYOLEFIN MATERIAL, SAID COPOLYMER MATERIAL CONSISTING OF ETHYLENE-VINYL ACETATE COPOLYMER CONTAINING 10 TO 80 MOL % OF ETHYLENE, WHICH COPOLYMERS HAS BEEN SAPONIFIED TO AN EXTENT OF AT LEAST 85 PERCENT AND SAID POLYOLEFIN MATERIAL IS SELECTED FROM THE GROUP CONSISTING OF POLYPROPYLENE AND POLYETHYLENE, SAID COPOLYMER MATERIAL AND SAID POLYOLEFIN MATERIAL BEING IN THE FORM OF FIBERS, SPLIT FIBERS, FILMS OR MOLDINGS.
 2. Tobacco smoke filters as claimed in claim 1 wherein said copolymer material and said polyolefin material are in the form of fibers.
 3. Tobacco smoke filters as claimed in claim 1 for use with tobacco smoking pipes.
 4. A tobacco smoke filter as claimed in claim 1 for attachment to a single cigarette.
 5. Tobacco smoke filters as claimed in claim 1 for use with a cigarette holder.
 6. Tobacco smoke filters as claimed in claim 1 which are cartridge filters.
 7. A tobacco smoke filter adapted for use with a tobacco smoke article and of a shape to be inserted in the smoke passage of such tobacco smoke article, said filter having a porosity of 50 to 85 percent and comprising as essential filter material ethylene-vinyl acetate copolymer containing 10 to 80 mol percent ethylene and having the vinyl acetate moiety thereof saponified to an extent of at least 85 percent, said filter material being in the form of fibers, split fibers, films or moldings.
 8. A tobacco smoke filter of claim 7 wherein said copolymer contains 20 to 65 mol percent ethylene and is in the form of fibers.
 9. A tobacco smoke filter of claim 8 wherein said saponification extent is at least 90 percent.
 10. A cigarette with attached filter comprising as essential filter material ethylene-vinyl acetate copolymer containing 10 to 80 mol percent ethylene and having the vinyl acetate moiety thereof saponified to an extent of at least 85 percent, said filter material being in the form of fibers, split fibers, films or moldings.
 11. The method of filtering tobacco smoke in a tobacco smoke article which comprises passing the tobacco smoke through a filter which comprises as essential filter material ethylene-vinyl acetate copolymer containing 10 to 80 mol percent ethylene and having the vinyl acetate moiety thereof saponified to an extent of at least 85 percent, said filter material being in the form of fibers, split fibers, films or moldings.
 12. The method of claim 11 wherein said filter contains a mixture of 80 to 20 parts by weight of fibers of said copolymer with 20 to 80 parts by weight of polyethylene fibers. 